The common-rail system has been applied for a long time in the fuel injection system of engines. The structure of the common rail for fuel injection is greatly constrained because it needs to withstand a high pressure. Since a cylindrical structure can withstand a higher pressure than other structures, the cylindrical structure is adopted for almost all existing common rails for fuel injection.
As the standards for exhaust emission in the countries all over the world are increasingly becoming more strict, more requirements are put forward for the urea injection system used for exhaust treatment. How to control the pressure in the urea injection system is a common technical problem in the industry.
In addition, it is a practice in the prior art that an engine is usually equipped with a urea injection system. The installation and control in such a configuration mode are both relatively complex.